A new benzofuranone and anti-HIV constituents from the stems of Rhus chinensis

A new benzofuran lactone, rhuscholide A (1), was isolated from the stems of Rhus chinensis, together with six known compounds: 5-hydroxy-7-(3,7,11,15-tetramethylhexadeca-2,6,10,11 tetraenyl)-2(3H)-benzofuranone (2), betulin (3), betulonic acid (4), moronic acid (5), 3-oxo-60-hydroxyolean-12-en-28-oic acid (6) and 3-oxo-60-hydroxyolean-18-en-28-oic acid (7). Based on 1D, 2D NMR (COSY, HMQC, HMBC) and mass (EI-MS, HR-EI-MS) spectral data, the structure of rhuscholide A was deduced to be 5-hydroxy-3-(propan-2-ylidene)-7-(3,7,11,15-tetramethylhexadeca-2,6,10,11-tetraenyl)-2(3H)-benzofuranone (1). Anti-HIV-1 bioassays in vitro revealed that compound 1 possesses significant anti-HIV-1 activity with an EC50 value of 1.62 mu M and a therapeutic index (TI) of 42.40. Compounds 2, 4, 5 and 7 showed moderate anti-HIV-1 activities with EC50 values of 3.70, 5.81, 7.49 and 13.11 mu M, respectively.